Supplementary Table 1: The sentinel hospital IDs and locations. There are 23 hospital sites that perform laboratory confirmation of V. cholerae in Bangladesh.
| 1 |
District Hospital Norshingdi |
Dhaka |
district |
| 2 |
Adhunik Sadar Hospital Habiganj |
Sylhet |
district |
| 3 |
District Sadar Hospital Cox’s Bazar |
Chittagong |
district |
| 4 |
Adhunik Sadar Hospital Naogaon |
Rajshahi |
district |
| 5 |
General Hospital Patuakhali |
Barisal |
tertiary |
| 6 |
Adhunik Sadar Hospital Thakurgaon |
Rangpur |
district |
| 7 |
District Sadar Hospital Satkhira |
Khulna |
district |
| 8 |
Dhaka Medical College Dhaka |
Dhaka |
tertiary |
| 9 |
Uttara Adhunik Medical College Hospital |
Dhaka |
tertiary |
| 10 |
Bangladesh Institute of Tropical and Infectious Diseases Chittagong |
Chittagong |
tertiary |
| 11 |
General Hospital Tangail |
Dhaka |
district |
| 12 |
General Hospital Narayanganj |
Dhaka |
district |
| 13 |
Sadar Hospital Chuadanga |
Khulna |
district |
| 14 |
General Hospital Meherpur |
Khulna |
district |
| 15 |
General Hospital Comilla |
Chittagong |
district |
| 16 |
Upazila Health Complex Chaugachha Jesssore |
Khulna |
subdistrict |
| 17 |
General Hospital Kusthia |
Khulna |
district |
| 18 |
Upazila Health Complex Madan |
Mymensingh |
subdistrict |
| 19 |
Upazila Health Complex Chhatak Sunamganj |
Sylhet |
subdistrict |
| 20 |
Upazila Health Complex Mathbariya |
Barisal |
subdistrict |
| 21 |
Upazila Health Complex Bakerganj |
Barisal |
subdistrict |
| 22 |
Health Complex Shibganj |
Rajshahi |
subdistrict |
| 23 |
icddr,b Cholera Hospital |
Dhaka |
icddrb |
Supplementary Table 2: Population living in the cholera surveillance zone.
| 10-20-30-30 |
50888584 |
0.3129697 |

Supplementary Figure 1: A. Median risk of V. cholerae seroincidence relative to a population-weighted mean by 5 km x 5 km grid cell. These relative risk estimates are bounded such that RRs above and below 2 and -2 were plotted as the values 2 and -2, respectively. The black marks indicate sentinel hospital locations. B. Map of the uncertainty of the seroincidence estimates measured by entropy by 5 km x 5 km grid cell. The black marks indicate the serosurvey sites from the cross-sectional survey conducted in 2015. C. Median number of estimated V. cholerae infections per grid cell in the previous year. The black marks indicate sentinel hospital locations. These estimates were calculated as the product of the median seroincidence risk and 2015 WorldPop population estimate in each grid cell. The black marks indicate sentinel hospital locations.

Figure 1: Cholera greyspots. The 5 km x 5 km grid cells that are colored are cells covered in the cholera surveillance zone. The greyed out grid cells are areas not captured by the national cholera surveillance system in Bangladesh, where we have little information on clinical cases of cholera.

Figure 2: A. Cholera risk map as categorized by the risk of seroincidence relative to a population-weighted mean by 5 km x 5 km grid cell. The map illustrates grid cells of High-Moderate-Low risk and the which grid cells are captured by the cholera surveillance zone (10-20-30-30km for subdistrict, district, and tertiary care, and icddr,b hospitals), indicated by the transparent buffers. B. Cholera risk map as categorized by the estimated number of V. cholerae infections by 5 km x 5 km grid cell. The black marks indicate sentinel hospital locations and the transparent buffers overlayed represent the cholera surveillance zone.

Figure 3: A. Bar plot of the number of people and number of infections in the Bangladesh population and in the cholera surveillance zone living in high-moderate-low risk areas as defined by relative seroincidence risk and absolute number of infections risk measures. B. Bar plot of the percentage of the population and percentage of infection in Bangladesh and the cholera surveillance zone living in high-moderate-low risk areas using the relative seroincidence risk and absolute number of infections as measures of risk.

Supplementary Figure 3:
Supplementary Table 3: Population living in each risk category. The population living in high, moderate, and low risk areas according to relative seroincidence risk across Bangladesh.
| High |
9207436 |
| Moderate |
98962248 |
| Low |
54429387 |
Table 1: Part 1. Number and percent infections that may be captured in cholera surveillance zones. The percent infected represents the percentage of infected individuals captured within the cholera surveillance zone out of all infected individuals in Bangladesh. Part 2. Number and percent infections that may be captured in cholera surveillance zones, categorized by relative risk. The infections in surveillance zone represents the percentage of infected people in high-moderate-low risk grid cells among all infections within the cholera surveillance zone. The population in surveillance zone represents the percentage of people living in high-moderate-low risk grid cells among all people within the cholera surveillance zone. The distribution should across risk categories should sum to 100% for each set of buffer sizes. Part 3. Number and percent infections that may be captured in Bangladesh, categorized by relative risk. The captured at-risk population represents the percentage of high-moderate-low risk populations captured by the cholera surveillance zone out of all high-moderate-low risk populations in Bangladesh. The captured infections represents the percentage of infections in high-moderate-low risk grid cells among all infections in high-moderate-low risk grid cells across Bangladesh.
| 10-20-30-30 |
50,888,584 |
6,802,113 |
13.4 |
28.7 |
| 10-20-30-30 |
High |
817,295 |
12.0 |
3,113,395 |
6.1 |
| 10-20-30-30 |
Moderate |
3,070,442 |
45.1 |
19,839,091 |
39.0 |
| 10-20-30-30 |
Low |
2,914,375 |
42.8 |
27,936,098 |
54.9 |
| 10-20-30-30 |
High |
3,113,395 |
817,295 |
33.8 |
32.2 |
| 10-20-30-30 |
Moderate |
19,839,091 |
3,070,442 |
20.0 |
20.3 |
| 10-20-30-30 |
Low |
27,936,098 |
2,914,375 |
51.3 |
48.2 |
Supplementary Table 4: Population living in each risk category. The population living in high, moderate, and low risk areas according to the number of infections across Bangladesh.
| High |
98723766 |
| Moderate |
54850878 |
| Low |
9024426 |
Table 2: Part 1. Number and percent infections that may be captured in cholera surveillance zones. The percent infected represents the percentage of infected individuals captured within the cholera surveillance zone out of all infected individuals in Bangladesh. Part 2. Number and percent infections that may be captured in cholera surveillance zones, categorized by the number of infections. The infections in surveillance zone represents the percentage of infected people in high/moderate/low risk grid cells among all infections within the cholera surveillance zone. The population in surveillance zone represents the percentage of people living in high/moderate/low risk grid cells among all people within the cholera surveillance zone. The distribution should across risk categories should sum to 100% for each set of buffer sizes. Part 3. Number and percent infections that may be captured in Bangladesh, categorized by the number of individuals infected with V. cholerae . The captured at-risk population represents the percentage of high/moderate/low risk populations captured by the cholera surveillance zone out of all high/moderate/low risk populations in Bangladesh. The captured infections represents the percentage of infections in high/moderate/low risk grid cells among all infections in high/moderate/low risk grid cells across Bangladesh.
| 10-20-30-30 |
50,888,584 |
6,802,113 |
13.4 |
28.7 |
| 10-20-30-30 |
High |
5,084,430 |
74.7 |
38,491,888 |
75.6 |
| 10-20-30-30 |
Moderate |
1,556,279 |
22.9 |
11,266,842 |
22.1 |
| 10-20-30-30 |
Low |
161,404 |
2.4 |
1,129,854 |
2.2 |
| 10-20-30-30 |
High |
38,491,888 |
5,084,430 |
39.0 |
34.9 |
| 10-20-30-30 |
Moderate |
11,266,842 |
1,556,279 |
20.5 |
19.9 |
| 10-20-30-30 |
Low |
1,129,854 |
161,404 |
12.5 |
12.3 |
Supplementary Table 5: A. Population living in high certainty areas in the cholera surveillance zone. B. The population living in high, moderate, and low risk areas according to the number of infections across Bangladesh living in areas of high certainty per the entropy threshold of relative seroincidence risk.
| 10-20-30-30 |
22841377 |
0.1404767 |
| High |
0 |
| Moderate |
5292801 |
| Low |
35316745 |
Table 3: Part 1. Number and percent infections in grid cells of high certainty that may be captured in cholera surveillance zones. The percent infected represents the percentage of infected individuals captured within the cholera surveillance zone out of all infected individuals living in areas of high predictive certainty in Bangladesh. Part 2. Number and percent infections in areas of high certainty that may be captured in cholera surveillance zones, categorized by relative risk. The infections in surveillance zone represents the percentage of infected people in high-moderate-low risk grid cells among all infections within the cholera surveillance zone. The population in surveillance zone represents the percentage of people living in high-moderate-low risk grid cells among all people within the cholera surveillance zone. The distribution should across risk categories should sum to 100% for each set of buffer sizes. Part 3. Number and percent infections with high predictive certainty that may be captured in Bangladesh, categorized by relative risk. The captured at-risk population represents the percentage of high-moderate-low risk populations captured by the cholera surveillance zone out of all high-moderate-low risk populations in Bangladesh. The captured infections represents the percentage of infections in high-moderate-low risk grid cells among all infections in high-moderate-low risk grid cells across Bangladesh.
| 10-20-30-30 |
22,841,377 |
2,285,990 |
10 |
52.5 |
| 10-20-30-30 |
Moderate |
161,827 |
7.1 |
1,133,109 |
5 |
| 10-20-30-30 |
Low |
2,124,163 |
92.9 |
21,708,268 |
95 |
| 10-20-30-30 |
Moderate |
1,133,109 |
161,827 |
21.4 |
20.9 |
| 10-20-30-30 |
Low |
21,708,268 |
2,124,163 |
61.5 |
59.4 |
Table 4: A. The population not captured in the surveillance greyspots (cholera surveillance zone). B. The population not captured in the cholera surveillance zone or in areas where we have high certainty of our estimates of relative seroincidence risk. This is also referred to as information greyspots.
| Surveillance greyspot |
111,710,486 |
68.7 |
| Information greyspot |
98,954,591 |
60.9 |